Tiny parents

Can't sleep. I was, er, in the bathroom and a few simple lines came to me. I made some tea, munched some food, and came upstairs. Now I'm trying to recall them, and it's not coming out anywhere as crisp and clean. Here's my best effort at remembering:

Tiny parents, OR: At 32, 64, and 67, respectively

When did my parents become so
small, I don't remember this of them. They are as short now
as they were once endless.

My nephew, who is 3, kisses the white t-shirt holding my father's belly
and says, "Big tummy." I remember holding him there,
and wondering if he were Santa Claus.

Some eternal magic, a happy mystery,
this great love that does not end.
I was too young to understand
that they do.